The Pre-Elsterian Valley System in the Western Sudetes, Southwestern Poland, and Its Later Transformation

Home , Central Sudetes, Glacial series, Kwisa, Sudetes, Uniejowice, Western Sudetes

Geologia Sudetica, 1998, 31:317-328.

The pre-Elsterian valley system in the Western Sudetes, southwestern Poland, and its later transformation

Marek Michniewicz

Panstwowy Instytut Geologiczny, Oddziai Dolnoslqski, Jaworowa 19, 53-122 Wrodaw, Poland

Key words: buried valleys, fluvial pattern, glacial deposits, Elsterian glaciation

Abstract This paper presents a reconstruction of the pre-Elsterian fluvial pattern in the Western Sudetes Mts using borehole and geophysical data. These valleys were blocked by the advancing Elsterian ice sheet, enabling the proglacial lakes to be formed, and most of them were later covered by the ice sheet which entered into the mountain interior. The valleys are now filled with 5-15 m of 'pre-glaciaP fluvial gravels and a generally thick glacial series. The latter comprises a till and glaciofluvial and glaciolacustrine sediments, including varved clay. The former valleys occur along the axes of the present-day valleys or at their margins, or occur in watershed areas which have been recently abandoned. Post-Elsterian changes in valley pattern is due to the filling of old valleys and epigenetic incision of new valleys along the tributary valleys. The valley fragments which preserved their former position were deeply incised, with the almost complete removal of older deposits. Some fault activity has been documented for that time in the marginal zone of the Sudetes Mts. The Saalian ice sheet only entered the marginal part of the Sudetes Mts, and hydrographic changes from that time are smaller.

Manuscript received 15 April 1998, accepted 30 October 1998.

INTRODUCTION

The analysis of borehole and geophysical prospecting filling of the buried valleys. There are several views on the data indicated that buried valleys in the Western Sudetes age and the number of Scandinavian glaciations in the Su- (Fig. 1) contain sediments from only one glaciation, in- detes Mts.; the most important are: cluding one till, glaciolacustrine clay, silt and fine sand, 1. The Sudetes Mts were glaciated once during the El- which is usually underlain by fluvial gravel and coarse- sterian stage (Genieser, 1936; Schwarzbach, 1942; Dyjor, grained sand. Only at the mountain margin, in the north- 1991) ernmost part of the studied region, are there more till beds 2. The Sudetes Mts were glaciated once during the which suggest more than once ice sheet advance (Mich- early Saalian stage (Wilczynski, 1991) niewicz et al., 1995, 1996). A similar situation has been 3. The Sudetes Mts were glaciated twice and the ex- described in the adjacent part of Germany (Eissmann, tents of ice sheets during both advances were more or less 1975, 1994), where fluvial deposits at the base of buried the same, although the field data are very ambiguous valleys are interpreted as representing the Cromerian- (Jahn, 1960; Jahn & Szczepankiewicz, 1969) early Elsterian stage. Besides the buried valleys, there are 4. The Sudetes Mts were glaciated twice, but the ice some very deep troughs in the marginal part of the moun- sheets from different stages indicated various extents (Ma- tainous region, which may be interpreted as glacial tunnel coun & Kralik, 1995; Badura & Przybylski, 1998; Krzysz- valleys. Similar deep troughs are interpreted in Germany kowski & Stachura, 1998; Krzyszkowski & Biernat, 1998; as having formed during the Elsterian ice sheet advance Krzyszkowski et al., 1998). (KupetzeJrf/., 1989). This problem has not yet been solved satisfactorily The age of the buried valleys and their sediments in (fahn, 1995; Badura & Przybylski, 1998). It seems that the the western Sudetes has not been precisely established, glacial sediments of the interior of the western Sudetes rep- mainly due to the complete lack of organic deposits or resent the Elsterian stage. This interpretation takes into palaeontological findings. The crucial fact is, that all the account the great similarit-y of the studied sequences to valleys are covered by one till, and thus the age of the till those of southeast Germany, and the fact that the ice sheet gives the upper age boundary for the formation and the from the Elsterian glaciation indicated a more southern 318 M. MICHNIEWICZ

Fig. 1. The valley pattern of the western Sudetes and its foreland: 1 - pre-Elsterian valleys: a - main valleys, b - tributary valleys; 2 - pre-Elsterian valleys incised deeply during the Middle and Late Pleistocene: a - main valleys, b - tributary valleys; 3 - glacial tunnel valleys; 4 - faults zone of the margin of the Sudetes Mts; 5 - maximum extent of the Saalian glaciation: a - in Germany (after Kupetz etal, 1989), b - in western Sudetes (after Michniewicz etal., 1995,1996); 6- post-Elsterian (a) and post-Saalian (b) hydrographic changes in western Sudetes; 7 - anayled geological and geophysical cross sections, numbers indicate sections discussed in the paper; 8 - sheets of the 1:200,000 geological map: sheets Jelenia Gora (A), Bogatynia (B), Gubin (C), Zielona Gora (D), Leszno (E) and Walbrzych (F).

extent than the Saalian ice sheet in the wide region from Distribution and stratigraphy of the buried valleys in Leipzig to the Polish/German border (Eissmann, 1975, the Western Sudetes were recently presented in detail by 1994; Kupetz et al., 1989; Macoun & Kralik, 1995). The Michniewicz et al. (1995, 1996) and Michniewicz (1997). glacial sediments of the Saalian stage probably occur only This paper only presents the general results of this study at the margin of the Western Sudetes (Fig. 1). Thus the and its main aim is to reconstruct the fluvial pattern in the fluvial deposits under discussion are most probably of pre- Western Sudetes before the first Scandinavian glaciation in Elsterian age, and may roughly correlate with the Crome- this region (Fig. 1, 2). The results presented are based on rian-early Elsterian fluvial series of Eissmann (1975, 1994). the analysis of geophysical prospecting and 2649 boreholes However, some other authors, on the basis of data from which were done over the last few decades (Michniewicz et adjacent regions such as the northern part of the Czech al., 1995), as well as of the analysis of new geoelectrical Republic (Macoun & Kralik, 1995) or the Middle Sudetes profiles, which were performed during this project (Mzyk, (Krzyszkowski & Stachura, 1998; Krzyszkowski & Bier- 1995). There are 1234 measuring points along the new geo- nat, 1998) suggest that the early Saalian ice sheet had a electrical profiles, each located from 50 to 200 m apart. much wider extent. The profiles lie perpendicularly to the valleys, and have THE PRE-ELSTERIAN VALLEY SYSTEM IN THE WESTERN SUDETES 319

AB line spacing from 250 m at the margins to up to 1000 penetration down to 50-150 m. m in the axes of the valleys. These parameters gave depth

A RECONSTRUCTION OF THE PRE-ELSTERIAN VALLEY SYSTEM

THE PRE-BOBR VALLEY SYSTEM prospecting beyond the present-day valley between Papro- tek and Stara Bialka (Fig. 1) documented only bedrock, The upper course of the present-day Bobr river valley indicating a very stable position for the Bobr valley in this is located along the pre-Bobr valley system. In the south- region. In contrast, north of Kamienna Gora, the present- ernmost, non-glaciated region, the young fluvial deposits day and buried valleys have quite different locations. The are superimposed on the older fluvial gravels, forming a 15 former runs west, whereas the latter is present between m thick sequence near Bukowka (Fig. 3). More to the Ciechanowice and Kaczorow (Fig. 1). The buried valley north, near Janiszow, these young and old fluvial se- near Ciechanowice is filled with 10-15 m of fluvial gravels quences are separated by glaciolacustrine clay and silt (Fig. 4). The latter was deposited in the proglacial lake formed at the front of the Scandinavian ice sheet. Geophysical

Fig. 3. Geological cross section (no. 2) through the Bobr valley near Bukowka. Location in Fig. 1.7- location of the boreholes, 2 - the base of Quaternary deposits, 3 - location of the geophysical measuring points, 4 - faults, 5 - lithological boundaries, 6 - lithostratigraphic boundaries. Lithology: 7 - brown coal, 8 - varved clay, 9 - varved silt, 10 - silt, 11 - sandy silt, 12 - fine- grained sand and silt, 13 - fine-grained sand, 14 - medium- and coarse-grained sand, 15 - mixed, fine- to coarse-grained sand, 16 - Fig. 2. Longitudinal profiles along the buried valleys of the west- pebble sand, 17 - pebble gravel, 18 - cobble gravel, 19 - till or ern Sudetes: pre-Bobr (A), pre-Prusicki Potok (C), pre-Kamienna glaciolacustrine diamictons, 20 - slope deposits, mainly diamic- and pre-Lomnica, pre-Kwisa (D) and pre-Nysa and pre-Witka (E). tons, 21 - artificial deposits. Stratigraphy: Q - Quaternary, H - / - the bottom surface of the valley axes, 2 - valley fragments Holocene, B - Weichselian, W - late Saalian (Wartanian), O - glacially incised during the Elsterian glaciation, 3 - the base of early Saalian (Odranian), M - Holsteinian, E - Elsterian; Li- Quaternary deposits in tunnel valleys, 4 - valley fragments in- thological indexes on cross sections: d - fine-grained colluvium, r cised during the post-Elsterian time, 5 - position of the base of - coarse-grained colluvium, 1 - loess, li - lacustrine deposits, b - Quaternary deposits in boreholes, 6 - interpreted position of the glaciolacustrine deposits (bd - lower, bg - upper), fg - glaciofluvial base of Quaternary deposits in geophysical profiles, 7 - other deposits (fga - lower, fgg - upper), g - glacial deposits (till), f - boreholes. fluvial deposits. 320 M. MICHNIEWICZ

Fig. 4. Geological cross section (no 3) through the pre-Bobr valley near Janiszow. Location in Fig. 1, explanations in Fig. 3.

Fig. 5. Geological cross section (no 4) through the pre-Bobr valley near Ciechanowice. Location in Fig. 1, explanations in Fig. 3.

Fig. 7. Interpretation of the geological structure (section no 6) of the pre-Bobr valley near Wojcieszow based on geophysical data. Location in Fig. i, explanations in Fig. 3.

Kaczawa valley, with the probable exception of a short fragment near Swierzawa, and then turns west, to the present-day Skora valley (Fig. 1). Boreholes were done very rarely in this region and the cross sections (Fig. 8) are based practically only on geophysical data. Nevertheless, it seems that between Sokolowiec and Pielgrzymka the val- Fig. 6. Interpretation of the geological structure (section no 5) of ley contains a similar sediment sequence to its upper the pre-Bobr valley near Swidnik based on geophysical data. Lo- cation in Fig. 1, explanations in Fig. 3. courses, with lower fluvial gravels and an upper glacial series, although there are no glaciolacustrine deposists (Fig. 8). Further north, at the margin of the mountainous region, the glacial deposits are highly reduced, having been and about 40 m of glacial deposits, glaciolacustrine clay completely eroded in the valley and only occurring be- and silt and a till (Fig. 5). The till bed was found at the yond it (Fig. 8) (Michniewicz etal., 1995, 1996). One bore- surface of the abandoned valley. hole, at Zagrodno (Fig. 1), is probably in a tributary-valley The middle course of the pre-Bobr valley is located of the pre-Prusicki Potok (Fig. 2). along the present-day Kaczawa river valley from Kaczo- The pre-Bobr valley is glacially re-modelled beyond row to Wojcieszow, where it was documented during sev- the mountaineous region, as documented at Krzywa (Fig. eral geophysical profiles (Fig. 1). Cross sections inter- 9). The boreholes there indicate a deep (bottom at about 60 preted from this geophysical data show that the buried val- m a.s.l.) and up to 2 km wide trough filled with glacial ley contains similar sequences to Ciechanowice, i.e. about deposits. In contrast with the mountainous region, the se- 10 m of fluvial gravels at the bottom and 50-100 m of quence contains glacial deposits from at least two, and glacial deposits at the top (Fig. 6, 7). The fluvial gravels do probably from three glaciations, with two or three tills not contain Scandinavian material, and were named the (Sztromwasser, 1997). The lower part of this sequence is 'preglaciaP series by Genieser (1936). North of Wojcie- very like the sequences of the tunnel valleys described by szow, the pre-Bobr valley is parallel to the present-day Kupetz et al. (1989) in east Germany. The valley course THE PRE-ELSTERIAN VALLEY SYSTEM IN THE WESTERN SUDETES 321

Fig. 8. Interpretation of the geological structure of the pre-Bobr and pre-Kamienna valleys near Twardocice (upper section - no 7) and near Uniejowice (lower section - no 8) based on geophysical data. Location in Fig. 1, explanations in Fig. 3.

Fig. 9. Geological cross section through the tunnel valley near Krzywa (section no 9). Location in Fig. 1, explanations in Fig. 3. 322 M. MICHNIEWICZ

bor.1A bor13

Fig, 10. Geological cross section (no 10) through the pre-Lomnica valley near Jelenia Gora Location in Fig, 1, explanations in Fig. 3.

northwards is poorly documented; the geophysical pro- THE PRE-KAMIENNA-LOMNICA VALLEY files and geological data presented by Szafajdewicz (1985) SYSTEM suggest the a N-S trend, although the trough must be very sinuous as there are numerous outcrops of Pliocene sedi- Before the Elsterian glaciation, the Jelenia Gora Basin ments at the surface (Sztromwasser, 1997). was drained by two rivers: the pre-Lomnica and the pre- Kamienna. The buried valley of the former was documented near Jezow Sudecki (Fig. 10) and of the latter near Jelenia Gora (Fig. 11). In both cases, the buried valleys occur beyond the present-day valleys of Lomnica and Ka- mienna, and both of them contain 'preglacial' fluvial gravels and thick glaciolacustrine series and with a till bed at the surface (Michniewicz, 1993). The till is locally overlain by glaciofluvial sediments. The original borehole descrip- tion suggested that the glaciolacustrine clay and silt was from 1 to 2 m thick. However, data from the Jelenia Gora brickyard (Fig. 11) suggest that these deposits may be up to several metres thick and that they may contain other types of sediments, including diamicton beds, besides the lami- nated clay and silt (varved clay). It is possible that the boreholes, instead of a thick till with lenses of fine-grained material, contain a strongly lithologically variable glaciolacustrine series (Fig. 10, 12). A similar thick glaciolacustrine series was described by Genieser (1936) near Siedl^cin. West of Jezow Sudecki, the pre-Lomnica and pre-Ka- mienna valleys join into one valley (Fig. 12), which trends parallel to the present-day Bobr valley in the northern part of the Jelenia Gora Basin between Jezow Sudecki and Sie- dl^cin (Fig. 1). Jahn (1995) suggested that this valley trends from Siedl^cin directly to the north. However, geophysical research did not confirm such a position for the buried valley, which must have joined the present-day Bobr valley before Pilichowice. There is no trace of any buried valley in the present-day Bobr valley or on its margin between Pilichowice and Sobota. The young valley incised down to a depth of 30 m, and the sediments of the old valley were probably completely eroded in this region. Milewicz (1985) found some older fluvial deposits at sur- Fig. 11. Geological cross section (no 12) through the pre-Ka- rounding uplands only near Przezdzierza and Sobota. mienna valley near Jelenia Gora. Location in Fig. 1, explanations These deposits occur at about 240 m a.s.l. The geophysical in Fig. 3. profile near Sobota (Fig. 13) indicated a shallow valley THE PRE-ELSTERIAN VALLEY SYSTEM IN THE WESTERN SUDETES 323

Fig. 14. Geological cross section (no 14) through the pre-Kwisa valley near Krobica. Location in Fig. 1, explanations in Fig. 3.

Fig. 12. Geological cross section (no 11) through the pre- Kamienna-Lomnica valley near Jezow Sudecki. Location in Fig. 1, explanations in Fig. 3.

Fig. 15. Geological cross section (no 15) through the pre-Kwisa valley near Gryfow. Location in Fig. 1, explanations in Fig. 3.

contains a similar sediment sequence to the pre-Bobr and pre-Kamienna valleys, namely the lower fluvial gravel, up to 10-15 m thick, glaciolacustrine clay and silt and a glacial till. The glacial deposits reach thickness up to 30 m (Fig. Fig. 13. Interpretation of the geological structure (section no 13) 15). The glaciolacustrine series is up to 2 m thick and lies of the pre-Kamienna valley near Sobota based on geophysical directly below the till (Michniewicz et al, 1995). Another data. Location in Fig. 1, explanations in Fig. 3. glaciolacustrine series was found in the tributary valley - the pre-Oldza between Ubocze and Oleszna (Fig. 1), where clay and silt occur above the till (Fig. 16). Except for filled with gravels, which may represent a fragment of the the different positions of the glaciolacustrine deposits, pre-Elsterian valley system. Its bottom is at about 225 m both the main and tributary valleys contain very similar a.s.l. and correlates well with the position of the bottom of sediment sequences and indicate similar depths and widths. the buried valley in its upper and lower courses (Fig. 2). It is possible that, as in the Jelenia Gora Basin, the bore- The valley near Sobota currently has no glacial deposits on hole logs gave oversimplified lithological descriptions, top, which may be explained as a result of Late Pleistocene and, in fact, the valleys contain only the one lithologically erosion. A similar position for the buried valley was also variable glaciolacustrine series. suggested by Genieser (1936). The buried valley continues to the east and northeast, through Dtuzec and Rochow to The pre-Kwisa valley most probably trended north- Twardocice, where it joins the pre-Bobr valley (Fig. 1, 8). west of Gryfow, through Olszyna to Uniegoszcz, as documented by geophysical profiles (Fig. 1). Jahn (1995) suggested that the pre-Kwisa valley trended from Olszyna di- THE PRE-KWISA VALLEY SYSTEM rectly to the west. This is probably an incorrect interpretation, as the buried valley was also found northwest of Ol- A shallow buried valley was found on the left side of szyna, near Radostow and Uniegoszcz. The cross section the upper course of the present-day Kwisa river valley near Uniegoszcz (Fig. 17) suggests that there are no glacio- (Fig. 1). It contains fluvial gravels up to 10 m thick topped lacustrine sediments in this part of the valley, which is by a till bed (Fig. 14). The valley continues to the NE mainly occupied by fluvial (lower part) and glaciofluvial reaching Gryfow Sl^ski (Schwarzbach, 1942), where it (upper part) gravels. The occurrence of the till bed is not 324 M. MICHNIEWICZ

along the present-day Kwisa valley to the NE. However, the present-day valley is here very deep and possible old fluvial deposits were eroded. The buried valley was documented again near Zabiocie and Mierzwin (Fig. 1), although there the valley practically only contains sand and gravel (Fig. 17). The valley continues to the NE, through Bolesiawiec to Krasnik (Fig. 1). Further north, the position of the pre-Kwisa valley is not well documented. It may trend to the north to Krzyzowa, or to the east to Krzywa (Berezowska & Berezowski, 1982, 1985). The last case is more probable, as boreholes indicated deep troughs, similar to those documented at Krzywa (Sztromwasser, 1997) (Fig. 9). They may represent the glacially re-modelled pre-Elsterian valleys. Fig. 16. Geological cross section (no 16) through the pre-Oldza valley near Oleszna Podgorska. Location in Fig. 1, explanations in Fig. 3. THE PRE-NYSA LUZYCKA VALLEY SYSTEM The upper course of the pre-Nysa Luzycka valley is in certain, although possible. The geoelectrical prospecting Germany (Fig. 1). This valley crosses the present-day Nysa did not show unambiguous characteristics (Mzyk, 1995) valley near Ujazd and continues to the northeast. The val- and only one borehole at Olszyna, which is located in the ley contains fluvial sand and gravel and a till bed (Fig. 18). valley, does not contain a till. Eissmann (1975) suggested more southward position for The course of the pre-Kwisa valley north of Unie- the valley and its turning to the northwest, again to Ger- goszcz is very ambiguous. Only directly NE of Unie- many. Recent investigations suggest that the pre-Nysa Lu- goszcz are some shallow troughs filled with gravels, simi- zycka valley trends continuously to the northeast and lar to those of the pre-Kamienna valley near Sobota (Fig. north, from Ujazd through Zarska Wies (Fig. 19) and 13). Michnie wicz & Wojtkowiak (1983) suggested that the Czerwona Woda (Fig. 20) to W^gliniec (Fig. 1). palaeovalley trends to the NW crossing the Slawniowicki The boreholes near Czerwona Woda comprises be- WaJ hills, but the geophysical prospecting work did not sides the lower fluvial gravels and the Elsterian till, and confirm this view (Mzyk, 1995). There is no buried valley other glacial deposits, namely glaciofluvial gravel and sand, in this region, and the low position of the base of the Pleis- glaciolacustrine silt and an upper till, which represents, tocene deposits near Pisarzowice and Wesotowka is prob- most probably, the Saalian glaciation (Fig. 20). The upper- ably due to glacial erosion (Fig. 1) (Berezowska & Bere- most glacial series corresponds with deposits found in the zowski, 1963). Thus, the old valley must have trended Slawnikowicki Wai hills (Fig. 1).

Fig. 17. Cross sections through the pre-Kwisa valley near Radostow (upper section, no 17, interpreted from geophysical data) and near Zabiocie (lower section, no 18, interpreted from borehole data). Location in Fig. 1, explanations in Fig. 3. THE PRE-ELSTERIAN VALLEY SYSTEM IN THE WESTERN SUDETES 325

Fig. 18. Interpretation of the geological structure (section no 19) of the pre-Nysa Luzycka valley near Ujazd based on geophysical data. Location in Fig. 1, explanations in Fig. 3.

Fig. 19. Geological cross section (no 20) through the pre-Nysa Luzycka valley near Zarska Wies. Location in Fig. 1, explanations Fig. 20. Geological cross section (no 21) through the pre-Nysa in Fig. 3. Luzycka valley near Czerwona Woda. Location in Fig. 1, explanations in Fig. 3.

Beyond the mountaineous region, near W^gliniec, the pre-Elsterian Nysa Luzycka valley was glacially remod- elled. The glacial trough, which probably contains pre-El- (Fig. 1, 21) (Michniewicz et al., 1995). It is also possible sterian fluvial sediments, was only documented by geo- that the trough represents a glacially re-modelled valley physical methods. It is a narrow trough filled with sands and/or tunnel valley, as suggested by Urbanski (1996). which occur below the lowest till in the region (Fig. 21). The base of the valley occurs about 50 m lower than at Czerwona Woda, which probably reflects displacement along the fault line separating the Sudetes from its foreland

Fig. 21. Geological cross section (no 22) of the marginal zone of the western Sudetes with the remodeled pre-Nysa Luzycka valley and glacial tunnel valley near W?gliniec Location in Fig. 1, explanations in Fig. 3. 326 M. MICHNIEWICZ

THE PRE-WITKA VALLEY SYSTEM

Geological and geophysical investigations near Radz- imow indicated the occurrence of a thick, extensive sandy- gravelly series (Berezowska & Berezowski, 1965; Mzyk, 1995). Originally, these deposits were interpreted as representing the Neogene series (Michniewicz etal., 1995; Mich- niewicz et al., 1996). However, Scandinavian material was recently found within this series in the Zawidow borehole Fig. 22. Interpretation of the geological structure (section no 23) 0. Badura & B. Przybylski,pers. information). The revised of the pre-Witka valley nad glacial tunnel valleys near Radzimow interpretation of the geophysical profile is presented in based on geophysical data. Location in Fig. 1, explanations in Fig. Fig. 22. It seems that there is a set of from 20 to 90 m deep 3. troughs which are filled with sands or gravels. The occurrence of a till is also possible. These troughs probably rep- Geophysical research indicated that the buried valley resent a tunnel valley system cut into the bedrock during is sinuous (Fig. 1). The pre-Witka valley trends at first to the Elsterian glaciation. Some shallower troughs may rep- the northeast and then to the west and north, through resent the remnants of the pre-Elsterian valley system (Fig. Mikuiowa and Studniska to Jerzmanki, where it joins the 22). Similar troughs were also described by Macoun & pre-Nysa Luzycka valley. Its geological structure is there Kralik (1995) between Visnova and Frydlant, several kilo- very similar to the pre-Nysa Luzycka valley near Ujazd metres to the south. (Fig. 18).

MAIN FEATURES OF THE PRE-ELSTERIAN VALLEYS AND THEIR SEDIMENTS

An analysis of the longitudinal profiles of the bottoms It seems that the position of the pre-Elsterian valley of the analysed buried valleys shows that they form uni- bottoms drops rapidly at the boundary between the moun- form downvalley inclined surfaces that can easily be inter- tainous region and its foreland (Fig. 2). The height differ- preted as fluvial surfaces. The only exceptions are the val- ence is from about 30-35 m to 50 m over very short dis- ley fragments beyond the mountainous region (Fig. 2). tances (Fig. 2), which may be interpreted as having formed The valleys generally have four fragments, each with a dif- due to faulting and the downthrow of the lowland valley ferent morphology and different valley fill. These are: fragments. The northern margin of the Western Sudetes 1. valley fragments of the high mountainous region contains a set of faults with different orientations, and this located beyond the glaciated area; these valleys are usually fault zone continues to the west, forming the Main Lusa- narrow, with the present-day valleys often in superposi- tian Fault Zone. Viete (1961) described very distinct fea- tion, and containing no glacial sediments between fluvial tures of Pleistocene faulting along this zone, and it seems, horizons. that the faults of the Western Sudetes might have been ac- 2. valley fragments of the high mountainous region tive at the same time. located within the glaciated area; these valleys are usually The thicknesses of the glacial deposits which fill the located beyond the present-day valleys or on their margins buried valleys vary from a few metres to more than 100 m. and are wider and deeper and are buried beneath a thick These deposits are also lithologically variable. Besides till, glacial deposit or at least separated from the younger flu- the glacial series consists of glaciofluvial sand and gravel vial series by glacial sediments. Almost all these valleys and glaciolacustrine sediments. The latter are especially li- contain glaciolacustrine sediments, often varved clays, sug- thologically variable with varved clays in some valleys, gesting the occurrence of proglacial lakes in the valleys through massive clay and silts, to fine- and medium-grai- prior to the final ice sheet advance into the mountain inte- ned sand and diamicton beds. The thickness of the glacio- rior. lacustrine sediments is also variable, from 40 m near Cie- 3. valley fragments of the low mountainous region lo- chanowice (pre-Bobr), to 18 m near Siedl?cin (pre-Kamien- cated near the margin of the Sudetes Mts; these valley frag- na) and only 1-3 m near Gryfow Sl^ski (pre-Kwisa). There ments are much less developed, sometimes being very are no glaciolacustrine sediments in the pre-Nysa Luzycka wide and shallow and filled with only sand and gravel, oc- valley. The glaciolacustrine deposits are thin or do not oc- casionally topped by a till. cur in all valleys in the marginal part of the Western Sude- 4. valley fragments located in the mountain foreland tes. The glaciolacustrine sediments generally occur at (lowland area); these are valley fragments re-modelled by higher altitude in the eastern zone (369 m a.s.l. near glacial and glaciofluvial erosion and the formation of tun- Ciechanowice and 293 m a.s.l. nera Siedl^cin) than in the nel valleys. The pre-Elsterian valleys can only locally be western zone (287 m a.s.l. near Gryfow and 170 m a.si. reconstructed. The occurrence of deep troughs near Radzi- near Jerzmanki), which directly follows the preglacial mow suggests that tunnel valleys may also occur in the low morphology. All these facts suggest that the proglacial mountainous region, although the structure near Zawi- lakes existed for a longer time in the high mountainous dow is the only one which is well documented. area which has narrow and isolated valleys, than in the low THE PRE-ELSTERIAN VALLEY SYSTEM IN THE WESTERN SUDETES 327 mountainous areas in the west and north. In the latter re- Moreover, some profiles suggest that the uppermost gion the valleys are wider and the watersheds much lower. part of the 'pre-glacial' gravels in the mountain interior are It seems that the Elsterian ice sheet advanced at first into interdigitated with glaciolacustrine sediments. At the the wide valleys of the pre-Nysa Luzycka and pre-Kwisa, mountain margin, the fluvial and glaciofluvial sediments soon reaching its maximum position, whereas the rela- are very similar to each other and they often cannnot be tively narrow and isolated valleys of the pre-Kamienna and precisely separated. This suggests that at least the upper- pre-Bobr become occupied at the same time by proglacial most part, if not the all of the lower fluvial series was de- lakes, and were covered by ice sheet only during its last posited in front of an advancing ice sheet, and thus is, in phase. fact, of early Elsterian age.

MIDDLE AND LATE PLEISTOCENE CHANGES IN THE VALLEY PATTERN

The main changes in the valley pattern took place di- being buried by a thick glacial sequence. In this case, the rectly after the Elsterian glaciation. They are presented in majority of the new valleys are of epigenetic origin and Fig. 1. These are: they were created during deglaciation. The new valley po- 1. formation of the Ciechanowice gorge and piracy of sitions are due to the primary outflow of glaciofluvial the upper Bobr to the Jelenia Gora Basin, where it joined water through the tributary valleys and their subsequent the Kamienica and Lomnica valleys, and the formation of incision. the gorge near Pilchowice and the shifting of the valley The Saalian ice sheet only extended to the margin of into its recent position, the Western Sudetes. Only some minor changes in valley 2. formation of the new Bobr-Kamienna valley near pattern can be documented for post-Saalian times; these Sobota, which trends to the northwest, and the abandon- are: ing the former valley which trended to the northeast, 1. shifting of the Kwisa valley near Nowogrodziec to 3. formation of the new valleys of the Kaczawa and the north, to its present-day position, Skora rivers which partly used the pre-Elsterian Bobr val- 2. shifting of the Skora valley near Zagrodno to the ley, east. 4. formation of the gorge between Gryfow and Lesna Besides the changes in valley pattern, the formation of and the piracy of the Kwisa river to the west, the new valleys and river piracy, there are some other im- 5. formation of the new Kwisa valley near Nowogro- portant changes in the old valleys. The valley fragments dziec, which trends to the northwest and the abandoning which are stable and did not change their position, were of former valley which trended to the northeast, deeply incised during the next stages of valley formation. 6. formation of the new Nysa Luzycka and Witka val- Any pre-Elsterian deposits, except in the uppermost valley leys, which trend to the north and northwest and the aban- courses, were usually completely removed from them. doning the former valleys, which trended to the northeast Such valley fragments occur along the Bobr river between and north. Pilchowice and Sobota and between Mierzwin and Bole- It seems that all these changes were not due to tectonic stawiec, along the Kaczawa river near S^dziszow, and activity, even if the river deflections took place near the along the Kwisa river near Mirsk and between Uniegoszcz fault lines, but that they were the result of the old valleys and Nowogrodziec (Fig. 1).

REFERENCES

BADURA, J. & PRZYBYLSKI, B., 1998. Zasi?gi Udolodow ple- Wydawnictwa Geologiczne, Warszawa. jstocenskich i deglacjacja obszaru mi?dzy Sudetami a Walem DYJOR, S., 1991. Wpfyw ewolucji paleogeograficznej na rozwoj Sl^skim [Extent of the Pleistocene ice sheets and deglaciation zlodowacen w Polsce Zachodniej. In: Kostrzewski, A. (ed.), between the Sudeten and the Silesian Lowland].. Biuletyn Geneza, litologia i stratygrafia utworow czwartorzqdowyck., Panstwowego Instytutu Geologicznego, 385: 9-28. Zeszyty Naukowe Uniwersytetu im. Adama Mickiewicza w BEREZOWSKA, B. & BEREZOWSKI, Z„ 1963. Szczegolowa Poznaniu, Seria Geografia, 50: 419-433 {in Polish only}. mapa geologiczna Sudetow 1:25 000, Arkusz Siekierczyn. Wy- EISSMANN, L., 1975. Das Quartar der Leipziger Tieflandsbucht dawnictwa Geologiczne, Warszawa. und angrenzender Gebiete um Saale und Elbe - Model eine BEREZOWSKA, B. & BEREZOWSKI, Z„ 1965. Objasnienia Landschaftsentwicklung am Rand der europaischen Konti- do Szczegolowej mapy geologicznej Sudetow 1:25 000, nentalvereisung. Schriftenreibe fur geologische Wissenschaften, Arkusz Zawidow. Wydawnictwa Geologiczne, Warszawa 2: 1-263. {in Polish only}. EISSMANN, L., 1994. Grundziige der Quartargeologie Mit- BEREZOWSKA, B. & BEREZOWSKI, Z., 1982. Szczegolowa teldeutschlands (Sachsen, Sachsen-Anhalt, Sudbrandenburg, mapa geologiczna Sudetow 1:25 000, Arkusz Boleslawiec. Wy- Thiiringen). Altenburger NaturwissenschaftlicheForschungen, dawnictwa Geologiczne, Warszawa. 7: 55-136. BEREZOWSKA, B. & BEREZOWSKI, Z„ 1985. Szczegolowa GENIESER, K., 1936. Studien zur Diluvialgeschichte des Bober- mapa geologiczna Sudetow 1:25 000, Arkusz Tomaszow Gorny. Katzbach-Gebirges und seiner Fliisse (Dissertation). Heinrich- 328 M. MICHNIEWICZ

Wilhelm-Dove-Gesellschaft, Liegnitz, 46pp. WOJTKOWIAK, A., 1995. Rozpoznanie geologiczne staro- JAHN, A., 1960. Czwartorz?d Sudetow. In: Teisseyre, H. (ed.), plejstocenskiej sieci dolin kopalnych Sudetow i ich przed- Regionalna Geologia Polski, t. Ill, Sudety,pat. 2, 358-418, Pol- pola - arkusz 1:200 000 Jelenia Gora. Maszynopis, Archiwum skie Towarzystwo Geologiczne, Krakow {in Polish only}. Oddzialu Dolnosl^skiego PIG, Wroclaw {in Polish only}. JAHN, A., 1995. Some remarks on hydrographical changes in MICHNIEWICZ, M, CZERSKI, M„ KIELCZAWA, J. & the Sudety Mountains. Quaestiones Geographicae, Special Is- WOJTKOWIAK, A., 1996. Staroplejstoceriska siec dolin sue, 4: 121-124. kopalnych Sudetow zachodnich i ich przedpola. Przeglad JAHN, A. & SZCZEPANKIEWICZ, S., 1967. Osady i formy Geologiczny, 44: 1232-1238 {in Polish only}. czwartorz?dowe Sudetow i ich przedpola. In: Galon, R. & MICHNIEWICZ, M. & WOJTKOWIAK, A, 1983. Elementy Dylik, J. (Eds.) Czwartorz?d Polski, 397-430, PWN, staroplejstocenskiej sieci hydrograficznej Sudetow na tie ak- Warszawa {in Polish only}. tualnego rozpoznania Polski potudniowo-zachodmej. Cz?sc KRZYSZKOWSKI, D. & STACHURA, R., 1998. Neotectoni- I: Rekonstrukcja staroplejstocenskiej sieci hydrograficznej. cally controlled fluvial features, Walbrzych Upland, Middle Kwartalnik geologiczny, 27: 865-866 {in Polish only}. Sudeten Mts., Southwestern Poland. Geomorphology, 22: 73- MILEWICZ, J., 1985. Szczegolowa mapa geologiczna Sudetow 91. 1:25000, Arkusz Wlen. Wydawnictwa Geologiczne, War- KRZYSZKOWSKI, D., BADURA, J. & PRZYBYLSKI, B, szawa. 1998. Late Cainozoic evolution of the Nysa Klodzka river MZYK, S., 1995. Dokumentacja badan geofizycznych. In: Mich- system between Klodzko and Kamieniec Z^bkowicki, Sude- niewicz, M., Czerski M., Kiefczawa, J. & Wojtkowiak A., tes Mts, Southwestern Poland. Geologia Sudetica, 31: 133- (Eds) Rozpoznanie geologiczne staroplejstocenskiej sieci 155. dolin kopalnych Sudetow i ich przedpola - arkusz 1:200 000 KRZYSZKOWSKI, D. & BIERNAT, J, 1998. Terraces of the Jelenia Gora. Maszynopis, Archiwum Oddziatu Dolno- Bystrzyca River Valley, central Sudetes, and their deforma- sl^skiego PIG, Wroclaw {In Polish only}. tion along the Sudetic Marginal Fault. Geologia Sudetica, 31: SCHWARZBACH, M„ 1942. Das Diluvium Schlesiens. Neues 241-258. Jahrbuch fiir Mmeralogie, Geologie und Paldontologie, 86: KUPETZ, M., SCHUBERT, G., SEIFERT, A. & WOLF, L, 189-246. 1989. Quartarbasis, pleistozane Rinnen und Beispile glazi- SZALAJDEWICZ, J., 1985. Objasnienia do Szczegoiowej mapy tektonischer Lagerungsstorungen im Niederlausitzer Braun- geologicznej Polski 1:50 000, Arkusz Chocianow. Wydaw- kohlengebiet. Geprofil, Freiberg, 1: 2-17. nictwa Geologiczne, Warszawa {In Polish only}. MACOUN, J. & KRALIK, F., 1995. Glacial history of the SZTROMWASSER, E., 1997. Objasnienia do Szczegoiowej Czech Republic. In: Ehlers, J., Kozarski S. & Gibbard, P. mapy geologicznej Polski 1:50 000, Arkusz Chojnow. Panst- (Eds), Glacial deposits in north-east Europe, A.A. Balkema, wowy Instytut Geologiczny, Warszawa {In Polish only}. Rotterdam, 389-405. URBANSKI, K., 1996. Objasnienia do Szczegoiowej mapy geo- MICHNIEWICZ, M„ 1993. Czwartorz?dowe doliny kopalne w logicznej Polski 1:50 000, Arkusz Swi^toszow. Panstwowy rejonie Jeleniej Gory. Posiedzenia naukowe Panstwowego In- Instytut Geologiczny, Warszawa {In Polish only}. stytutu Geologicznego, 49 (1): 46-47 {in Polish only}. VIETE, G., 1961. Beitrage zur glacigenen und endogenen Tek- MICHNIEWICZ, M., 1997. Zmiany przebiegu sieci rzecznej Su- tonik im Quartar und Tertiar Nord-und Mitteldeutschlands. detow Zachodnich po ust^pieniu zlodowacen poludniowo- Bergakademie, Berlin, 5: 280-294. polskich. In: Krzyszkowski, D. & Przybylski, B. (Eds), Pro- WILCZYNSKI, R., 1991. Nowe dane na temat przetomu Nysy blemy zlodowacen srodkowopolskich w Polsce poludniowo- Kfodzkiej przez struktur? bardzk;} [New data on the Nysa zachodniej, Przewodnik IV Konferencji "Stratygrafia plejsto- Kioszka gorge in the Bardo structure]. Acta Universitatis cenu Polski", Wroclaw, p. 188 {in Polish only}. Wratislaviensis 1375, Prace Geologiczno-Mineralogiczne, 29: MICHNIEWICZ, M., CZERSKI, M„ KIELCZAWA, J. & 251-270.